The percentage of estrus induction and plasma LH concentrations were examined in 15 Azawak zebu cows submitted to two different estrus synchronization protocols. In the first treatment (T1, n = 9), the ... [more ▼]

The percentage of estrus induction and plasma LH concentrations were examined in 15 Azawak zebu cows submitted to two different estrus synchronization protocols. In the first treatment (T1, n = 9), the cows received a norgestomet ear-implant for 10 days associated with estradiol valerate, prostaglandin F2alpha (PGF2alpha) and pregnant mare serum gonadotropin (PMSG) injections. Treatment 2 (T2, n = 6) consisted in two PGF2alpha injections 11 days apart, followed by the administration of PMSG two days after the second prostaglandin injection. Blood samples were collected every three hours during five days after implant removal (T1) or PMSG injection (T2) for LH measurements. The proportion of induced estrus was higher in T2, but the difference was not significant. In general, the elapsed time until the estrus onset tended to be shorter in norgestomet-treated animals (35.9 ± 3.9 h) than in prostaglandin-treated ones (49.5 ± 5.8 h). Seven out of nine norgestomet-treated cows, and only two out of the six treated with PGF2alpha, presented a peak of LH. The mean interval from the end of treatments to LH peak tended to be longer in PGF2-treated females than in norgestomet-treated ones. One female presenting abnormally high LH concentrations after implant removal did not show a peak of LH during the observation period. [less ▲]

Specific RIA systems were developed and used to measure pregnancy-associated glycoprotein (PAG) concentrations during gestation and the postpartum period in Azawak Zebu cows. Twelve females were palpated ... [more ▼]

Specific RIA systems were developed and used to measure pregnancy-associated glycoprotein (PAG) concentrations during gestation and the postpartum period in Azawak Zebu cows. Twelve females were palpated per rectum and diagnosed as pregnant. Blood samples were taken at 5-10-day intervals from approximately Week 8 of gestation until Week 10 postpartum (pp). One Zebu cow (Z15) initially diagnosed as pregnant showed PAG concentrations lower than the assay sensitivity (<0.20 ng/ml) and did not calve. Another cow (ZSand) showed abnormally high PAG concentrations during gestation and was excluded from the general PAG profile. The 10 other Zebu cows exhibited a very similar PAG profile. In these animals, concentrations increased progressively from Week 8 to 35 of gestation (from 6.0 +/- 4.2 to 196.0 +/- 34.8 ng/ml), remaining relatively constant until Week 39 (210.8 +/- 74.8 ng/ml), when they increased sharply to reach their highest level (1095.6 +/- 607.2 ng/ml) at around parturition. After delivery, PAG concentrations declined significantly (P < 0.05) until Week 2 postpartum (348.4 +/- 85.6 ng/ml) and slowly until Week 10 postpartum. Our results revealed that the PAG pattern in Zebu cattle was similar to those of taurine breeds during the first two trimesters of pregnancy, but differed in the peripartum period. [less ▲]